use base64::{self, engine::general_purpose, Engine};

const S0: [u8; 256] = [
    0x3e, 0x72, 0x5b, 0x47, 0xca, 0xe0, 0x00, 0x33, 0x04, 0xd1, 0x54, 0x98, 0x09, 0xb9, 0x6d, 0xcb,
    0x7b, 0x1b, 0xf9, 0x32, 0xaf, 0x9d, 0x6a, 0xa5, 0xb8, 0x2d, 0xfc, 0x1d, 0x08, 0x53, 0x03, 0x90,
    0x4d, 0x4e, 0x84, 0x99, 0xe4, 0xce, 0xd9, 0x91, 0xdd, 0xb6, 0x85, 0x48, 0x8b, 0x29, 0x6e, 0xac,
    0xcd, 0xc1, 0xf8, 0x1e, 0x73, 0x43, 0x69, 0xc6, 0xb5, 0xbd, 0xfd, 0x39, 0x63, 0x20, 0xd4, 0x38,
    0x76, 0x7d, 0xb2, 0xa7, 0xcf, 0xed, 0x57, 0xc5, 0xf3, 0x2c, 0xbb, 0x14, 0x21, 0x06, 0x55, 0x9b,
    0xe3, 0xef, 0x5e, 0x31, 0x4f, 0x7f, 0x5a, 0xa4, 0x0d, 0x82, 0x51, 0x49, 0x5f, 0xba, 0x58, 0x1c,
    0x4a, 0x16, 0xd5, 0x17, 0xa8, 0x92, 0x24, 0x1f, 0x8c, 0xff, 0xd8, 0xae, 0x2e, 0x01, 0xd3, 0xad,
    0x3b, 0x4b, 0xda, 0x46, 0xeb, 0xc9, 0xde, 0x9a, 0x8f, 0x87, 0xd7, 0x3a, 0x80, 0x6f, 0x2f, 0xc8,
    0xb1, 0xb4, 0x37, 0xf7, 0x0a, 0x22, 0x13, 0x28, 0x7c, 0xcc, 0x3c, 0x89, 0xc7, 0xc3, 0x96, 0x56,
    0x07, 0xbf, 0x7e, 0xf0, 0x0b, 0x2b, 0x97, 0x52, 0x35, 0x41, 0x79, 0x61, 0xa6, 0x4c, 0x10, 0xfe,
    0xbc, 0x26, 0x95, 0x88, 0x8a, 0xb0, 0xa3, 0xfb, 0xc0, 0x18, 0x94, 0xf2, 0xe1, 0xe5, 0xe9, 0x5d,
    0xd0, 0xdc, 0x11, 0x66, 0x64, 0x5c, 0xec, 0x59, 0x42, 0x75, 0x12, 0xf5, 0x74, 0x9c, 0xaa, 0x23,
    0x0e, 0x86, 0xab, 0xbe, 0x2a, 0x02, 0xe7, 0x67, 0xe6, 0x44, 0xa2, 0x6c, 0xc2, 0x93, 0x9f, 0xf1,
    0xf6, 0xfa, 0x36, 0xd2, 0x50, 0x68, 0x9e, 0x62, 0x71, 0x15, 0x3d, 0xd6, 0x40, 0xc4, 0xe2, 0x0f,
    0x8e, 0x83, 0x77, 0x6b, 0x25, 0x05, 0x3f, 0x0c, 0x30, 0xea, 0x70, 0xb7, 0xa1, 0xe8, 0xa9, 0x65,
    0x8d, 0x27, 0x1a, 0xdb, 0x81, 0xb3, 0xa0, 0xf4, 0x45, 0x7a, 0x19, 0xdf, 0xee, 0x78, 0x34, 0x60
];

const S1: [u8; 256] = [
    0x55, 0xc2, 0x63, 0x71, 0x3b, 0xc8, 0x47, 0x86, 0x9f, 0x3c, 0xda, 0x5b, 0x29, 0xaa, 0xfd, 0x77,
    0x8c, 0xc5, 0x94, 0x0c, 0xa6, 0x1a, 0x13, 0x00, 0xe3, 0xa8, 0x16, 0x72, 0x40, 0xf9, 0xf8, 0x42,
    0x44, 0x26, 0x68, 0x96, 0x81, 0xd9, 0x45, 0x3e, 0x10, 0x76, 0xc6, 0xa7, 0x8b, 0x39, 0x43, 0xe1,
    0x3a, 0xb5, 0x56, 0x2a, 0xc0, 0x6d, 0xb3, 0x05, 0x22, 0x66, 0xbf, 0xdc, 0x0b, 0xfa, 0x62, 0x48,
    0xdd, 0x20, 0x11, 0x06, 0x36, 0xc9, 0xc1, 0xcf, 0xf6, 0x27, 0x52, 0xbb, 0x69, 0xf5, 0xd4, 0x87,
    0x7f, 0x84, 0x4c, 0xd2, 0x9c, 0x57, 0xa4, 0xbc, 0x4f, 0x9a, 0xdf, 0xfe, 0xd6, 0x8d, 0x7a, 0xeb,
    0x2b, 0x53, 0xd8, 0x5c, 0xa1, 0x14, 0x17, 0xfb, 0x23, 0xd5, 0x7d, 0x30, 0x67, 0x73, 0x08, 0x09,
    0xee, 0xb7, 0x70, 0x3f, 0x61, 0xb2, 0x19, 0x8e, 0x4e, 0xe5, 0x4b, 0x93, 0x8f, 0x5d, 0xdb, 0xa9,
    0xad, 0xf1, 0xae, 0x2e, 0xcb, 0x0d, 0xfc, 0xf4, 0x2d, 0x46, 0x6e, 0x1d, 0x97, 0xe8, 0xd1, 0xe9,
    0x4d, 0x37, 0xa5, 0x75, 0x5e, 0x83, 0x9e, 0xab, 0x82, 0x9d, 0xb9, 0x1c, 0xe0, 0xcd, 0x49, 0x89,
    0x01, 0xb6, 0xbd, 0x58, 0x24, 0xa2, 0x5f, 0x38, 0x78, 0x99, 0x15, 0x90, 0x50, 0xb8, 0x95, 0xe4,
    0xd0, 0x91, 0xc7, 0xce, 0xed, 0x0f, 0xb4, 0x6f, 0xa0, 0xcc, 0xf0, 0x02, 0x4a, 0x79, 0xc3, 0xde,
    0xa3, 0xef, 0xea, 0x51, 0xe6, 0x6b, 0x18, 0xec, 0x1b, 0x2c, 0x80, 0xf7, 0x74, 0xe7, 0xff, 0x21,
    0x5a, 0x6a, 0x54, 0x1e, 0x41, 0x31, 0x92, 0x35, 0xc4, 0x33, 0x07, 0x0a, 0xba, 0x7e, 0x0e, 0x34,
    0x88, 0xb1, 0x98, 0x7c, 0xf3, 0x3d, 0x60, 0x6c, 0x7b, 0xca, 0xd3, 0x1f, 0x32, 0x65, 0x04, 0x28,
    0x64, 0xbe, 0x85, 0x9b, 0x2f, 0x59, 0x8a, 0xd7, 0xb0, 0x25, 0xac, 0xaf, 0x12, 0x03, 0xe2, 0xf2
];

const D: [u32; 16] = [
    0x44D7, 0x26BC, 0x626B, 0x135E, 0x5789, 0x35E2, 0x7135, 0x09AF,
    0x4D78, 0x2F13, 0x6BC4, 0x1AF1, 0x5E26, 0x3C4D, 0x789A, 0x47AC
];

struct ZucGenerator {
    // ZUC流密码生成器，参考国家标准实现
    s: [u32; 16],
    r1: u32,
    r2: u32,
    x: [u32; 4], 
}

fn contact(x: u32, y: u32) -> u32 {
    (x << 16) | (y & 0xFFFF)
}

fn s(x: u32) -> u32 {
    let x0 = (x >> 24) & 0xFF;
    let x1 = (x >> 16) & 0xFF;
    let x2 = (x >> 8) & 0xFF;
    let x3 = x & 0xFF;
    let y0 = S0[x0 as usize] as u32;
    let y1 = S1[x1 as usize] as u32;
    let y2 = S0[x2 as usize] as u32;
    let y3 = S1[x3 as usize] as u32;
    y0 << 24 | y1 << 16 | y2 << 8 | y3
}

fn l1(x: u32) -> u32 {
    x ^ x.rotate_left(2) ^ x.rotate_left(10) ^ x.rotate_left(18) ^ x.rotate_left(24)
}

fn l2(x: u32) -> u32 {
    x ^ x.rotate_left(8) ^ x.rotate_left(14) ^ x.rotate_left(22) ^ x.rotate_left(30)
}

fn add_with_mod(a: u32, b: u32) -> u32 {
    let c = a.wrapping_add(b);
    (c & 0x7FFF_FFFF).wrapping_add(c >> 31)
}

fn mul_with_mod(a: u32, k: u32) -> u32 {
    let a = a & 0x7FFF_FFFF;
    ((a << k) | (a >> (31 - k))) & 0x7FFF_FFFF
}


impl ZucGenerator {
    fn new(key: [u8; 16], iv: [u8; 16]) -> Self {
        let mut s: [u32; 16] = [0u32; 16];
        for i in 0..16 {
            s[i] = (key[i] as u32) << 23 | D[i] << 8 | iv[i] as u32;
        }
        Self {
            s,
            r1: 0,
            r2: 0,
            x: [0u32; 4],
        }
    }

    fn work_init(&mut self) {
        for _i in 0..32 {
            self.bit_reconstruction();
            let w = self.function_f();
            self.lfsr_with_initialisation_mode(w >> 1);
        }
        self.bit_reconstruction();
        self.function_f();
        self.lfsr_with_work_mode();
    }

    fn work_a_round(&mut self) -> u32 {
        self.bit_reconstruction();
        let z = self.function_f() ^ self.x[3];
        self.lfsr_with_work_mode();
        z
    }

    fn bit_reconstruction(&mut self) {
        let high_16 = |x: u32| (x >> 15) & 0xFFFF;
        let low_16 = |x: u32| x & 0xFFFF;
        self.x[0] = contact(high_16(self.s[15]), low_16(self.s[14]));
        self.x[1] = contact(low_16(self.s[11]), high_16(self.s[9]));
        self.x[2] = contact(low_16(self.s[7]), high_16(self.s[5]));
        self.x[3] = contact(low_16(self.s[2]), high_16(self.s[0]));
    }

    fn function_f(&mut self) -> u32 {
        let high_16 = |x: u32| (x >> 16) & 0xFFFF;
        let low_16 = |x: u32| x & 0xFFFF;
        let w = (self.x[0] ^ self.r1).wrapping_add(self.r2);
        let w1 = self.r1.wrapping_add(self.x[1]);
        let w2 = self.r2 ^ self.x[2];
        self.r1 = s(l1(contact(low_16(w1), high_16(w2))));
        self.r2 = s(l2(contact(low_16(w2), high_16(w1))));
        w
    }

    fn lfsr_with_initialisation_mode(&mut self, u: u32) {
        let mut v = mul_with_mod(self.s[15], 15);
        v = add_with_mod(v, mul_with_mod(self.s[13], 17));
        v = add_with_mod(v, mul_with_mod(self.s[10], 21));
        v = add_with_mod(v, mul_with_mod(self.s[4], 20));
        v = add_with_mod(v, mul_with_mod(self.s[0], 8));
        v = add_with_mod(v, self.s[0]);
        let mut s16 = add_with_mod(v, u);
        if s16 == 0 {
            s16 = (1 << 31) - 1;
        }
        for i in 0..15 {
            self.s[i] = self.s[i + 1];
        }
        self.s[15] = s16;
    }

    fn lfsr_with_work_mode(&mut self) {
        let mut v = mul_with_mod(self.s[15], 15);
        v = add_with_mod(v, mul_with_mod(self.s[13], 17));
        v = add_with_mod(v, mul_with_mod(self.s[10], 21));
        v = add_with_mod(v, mul_with_mod(self.s[4], 20));
        v = add_with_mod(v, mul_with_mod(self.s[0], 8));
        let mut s16 = add_with_mod(v, self.s[0]);
        if s16 == 0 {
            s16 = (1 << 31) - 1;
        }
        for i in 0..15 {
            self.s[i] = self.s[i + 1];
        }
        self.s[15] = s16;
    }

    #[allow(unused)]
    fn check_s(&self) {
        println!("check s:   ");
        for i in 0..16 {
            println!("  s[{}] = {:#x}", i, self.s[i]);
        }
    }

    #[allow(unused)]
    fn check_x(&self) {
        println!("check x:   ");
        for i in 0..4 {
            println!("  x[{}] = {:#x}", i, self.x[i]);
        }
    }

    #[allow(unused)]
    fn check_r(&self) {
        println!("check r:   ");
        println!("  r1 = {:#x}", self.r1);
        println!("  r2 = {:#x}", self.r2);
    }
}

fn translate_to_u32(input: &str) -> Vec<u32> {
    // PKCS7填充，返回u32数组
    let mut bytes = input.as_bytes().to_vec();
    let padding_size = 4 - bytes.len() % 4;
    bytes.extend(vec![padding_size as u8; padding_size]);
    let ret = bytes.chunks(4).map(
        |chunk| u32::from_be_bytes(chunk.try_into().unwrap())
    ).collect();
    ret
}

fn translate_to_string(input: &Vec<u32>) -> String {
    // 转换为base64格式字符串
    let mut bytes = Vec::new();
    for num in input {
        bytes.extend(&num.to_be_bytes());
    }
    general_purpose::STANDARD.encode(&bytes)
}

pub fn encryption(input: String) -> String {
    const KEY: [u8; 16] = [0; 16];
    const IV: [u8; 16] = [1; 16];
    let mut zuc_generator = ZucGenerator::new(KEY, IV);
    let plaintext = translate_to_u32(&input);
    zuc_generator.work_init();
    let mut encrypted_text: Vec<u32> = Vec::new();
    for i in 0..plaintext.len() {
        let k = zuc_generator.work_a_round(); 
        encrypted_text.push(k ^ plaintext[i]);
    }
    translate_to_string(&encrypted_text)
}
